Extended Data Fig. 4: The BSI normalizes gait parameters and supports walking on complex terrains.

a, Principal component (PC) analysis applied on kinematic and muscle activity parameters during walking on a treadmill with stimulation alone versus BSI. During stimulation alone conditions, a closed-loop controller based on motion sensors attached to the lower limbs determine the parameters of stimulation. Each dot represents a gait cycle. The bar plot reports the Euclidean distance in the PC space between each sample and the centroid of the healthy steps. (n = 119, n = 30 and n = 61 steps for healthy, EES only and BSI respectively, unpaired one-tailed t-test ***, P < 0.001). Compared to stimulation alone, the BSI enabled walking with gait features that were closer to those quantified in healthy individuals. This similitude is highlighted in the bar plots, which report the mean values of kinematic parameters with a high factor loading on PC1. b, Quantitative measure of step length while walking with crutches. Steps below 10 cm are considered failed as illustrated in the stick plot diagram. EES only condition showed significantly shorter step length due to increase of failed steps (n = 26, n = 43 for EES only and BSI respectively, Mann-Whitney U test one-tailed t-test **, P < 0.01). c, Photographs illustrating walking capacities, together with bar plots that report quantifications of performance during the execution of various walking paradigms, including walking up and down a ramp, climbing stairs, and walking with crutches overground. d) Walking on changing terrains with obstacles and different textures (6 surfaces), as illustrated in the scheme on the left. Conventions are the same as in previous figures. Decoding stability is shown by overlayed probability curves of right hip flexions over consecutive steps (n = 13 steps, Left accuracy = 0.89 +/− 0.1 std, w = 2.06 s +/− 0.6 s std), and Left accuracy (n = 13 steps, accuracy = 0.91 +/− 0.1 std, w = 2.06 s +/− 0.4 s std).